This invention relates to a wheelchair, and particularly to a collapsible wheelchair.
Collapsible wheelchairs have been provided for some time, the objective being to allow them to collapse in a simple and compact manner so that they can be easily stored and transported, for example, by loading into the boot of a car.
One known collapsing arrangement comprises a scissors-type hinge between the wheels which allows the chair to be collapsed by pushing the sides of the chair towards each other. The wheels may or may not be removable. In this arrangement, the seat is generally flexible so that it folds down as the sides are pushed towards each other. While this arrangement is usually quite simple to operate, it suffers from the disadvantage of the chair not being particularly compact when collapsed. Also, the seat is often not particularly comfortable because it is of a flexible material to allow folding as the chair is collapsed. A still further disadvantage is that because the hinging mechanism is at the core of the chair structure it reduces structural strength, particularly in the transverse direction. Further, over time play in the structure can arise due to wear.
Alternatively, as described in Soviet Union Patent Specification No. SU1814547, it is known to provide a collapsing arrangement whereby the backrest support folds down over the seat. However, such chairs are still quite bulky when collapsed and the arrangement is of limited benefit.
Finally, a general problem with existing collapsible wheelchairs is that they are quite heavy, and thus difficult to lift when collapsed.
The invention is therefore directed towards providing a wheelchair which is collapsible in a manner whereby the chair is very compact when collapsed.
Another objective is that the chair has a high structural strength.
A further objective is that the chair is relatively lightweight.
According to the invention, there is provided a collapsible wheelchair comprising a seat support, a backrest support, a lower leg support, and wheels on an axle, characterized in that, the backrest support and the lower leg support are each movable from an operative position to a collapsed position substantially parallel to the seat support.
By allowing the backrest support and the lower leg support to lie substantially parallel to the seat support, the wheelchair collapses in a very compact manner. There is no need to introduce a hinge between the wheels and there is therefore improved structural integrity.
In one embodiment, the backrest support and the lower leg support are movable by pivoting about the seat support. Pivoting is a very simple way of collapsing the chair, and pivot joints are also generally very reliable and durable.
In one embodiment, the lower leg support is movable by pivoting about a lower leg support pivot joint to lie underneath the seat support. This is a very simple and compact arrangement.
Preferably, the seat support comprises a front portion which extends downwardly and supports the lower leg support pivot joint at a lower end thereof. This is an important aspect of the invention as the front portion provides a large degree of strength and structural integrity for the front part of the chair, and it also serves the purpose of supporting a pivot joint for the lower leg support so that the lower leg support folds neatly up underneath the seat support in a compact manner. In this latter embodiment, the seat support front portion comprises a pair of spaced-apart longitudinal tubes extending downwardly.
In one embodiment, the lower leg support is configured to lie between the lower leg support pivot joint and the wheel axle or camber bar. This allows the lower leg support to rest between the seat support front portion and the wheel axle in a compact and convenient manner.
In one embodiment, the lower leg support pivot joint comprises a pivot pin between the lower leg support and the seat support, and a sleeve which is slidable between a locked position covering the pin and preventing lower leg support rotation and an unlocked position at which the pin is exposed and the lower leg support is free to pivot about the pin. The use of a slidable sleeve is a very inexpensive and simple way of locking the joint in a manner whereby the chair withstands the usual day-to-day forces transmitted from the front of the wheelchair.
Preferably, the sleeve is knurled for ease of operation. This allows a user to easily slide the sleeve between the locked and unlocked positions.
Preferably, the sleeve is held in the locked position by a bayonet fixture. This is a well-known and simple fixture.
Preferably, the lower leg support comprises a U-shaped bar, the lower part of which is a footrest. This is a simple construction which provides excellent strength in a simple and lightweight manner.
In one embodiment, the lower leg support further comprises a transverse brace extending between uprights. Such a brace provides a large degree of strength for the lower leg support, particularly to prevent it from twisting. Again, the brace does not add much weight or complexity to the wheelchair.
In one embodiment, the U-shaped bar uprights are mounted within a pair of outer sleeves for telescoping height adjustment. This is a very simple way of providing adjustment for the footrest.
Preferably, the seat support comprises a brace extending transversely between a pair of side members, and the lower leg support brace is offset with respect to the seat support brace when the chair is collapsed. These braces can allow a compact arrangement whereby they provide support for the chair when collapsed so that it is not easily damaged.
In one embodiment, the wheelchair further comprises a fastener to interconnect the lower leg support and the seat support in the collapsed position to prevent inadvertent opening. This is a simple way of preventing inadvertent opening. The fastener can, for example, be connected between the braces on the seat and lower leg supports.
Preferably, the wheel axle is mounted on a adjustable axle support for height adjustment. This allows excellent versatility.
In one embodiment, the axle support comprises a pair of uprights interconnected by a transverse bar connected to the wheel axle. This arrangement provides high strength in a simple manner.
In one embodiment, the axle is adjustable in the longitudinal direction on the axle support. This also provides versatility in a simple manner.
In one embodiment, the uprights are mounted for telescoping height adjustment. This is a simple way of allowing height adjustment.
In one embodiment, the wheelchair further comprises a longitudinal brace extending between the lower leg support and the seat support, the longitudinal brace being removable. Such a brace adds additional structural strength, which, for example, is desirable in some applications such as sports use.
In one embodiment, the backrest support is connected to the seat support by a pivot joint. Preferably, the backrest support comprises a lock having a pair of locking pins biased into a locked position and releasible by operation of an actuator. This is a very simple release arrangement.
In one embodiment, the backrest support comprises at least one plate extending in the longitudinal direction, each plate being connected to the seat support by a pivot joint and by a lock positioned rearwardly of the pivot joint and being secured to a backrest support main body between the joint and the lock. These plates provide high strength connecting the backrest and seat supports together, and allow the backrest support to be folded down to overlie the cushion of the seat support.